Slurry pump



Nov. 12, 1968 w. F. SWANTON SLURRY PUMP Filed Feb. 17, 1967 mwnEOI INVENTOR. WALTER F. SWANTON ATTORNEY United States Patent O 3,410,222 SLURRY PUMP Walter Frederick Swanton, Avon, N.Y., assignor to Bitter Pfaudler Corporation, Rochester, N.Y., a corporation of New York Filed Feb. 17, 1967, Ser. No. 616,834 7 Claims. (Cl. 103240) ABSTRACT OF THE DISCLOSURE A pump for slaughter house waste materials and the like which is steam and/or compressed air operated. The pump includes two chambers, one larger than the other. The larger chamber receives the charge of material to be pumped while the smaller chamber receives a charge of compressed air and/ or steam which is released for expansion into the larger chamber to discharge the material therein under rapidly diminishing pressure. The pump is controlled by a pressure switch and timer; the timer controlling the charging of the larger chamber with waste material and initiating the introduction of a charge of compressed gas to the smaller chamber; the pressure switch stopping the introduction of a charge of compressed gas into the smaller chamber, controlling the discharge of slaughter house waste materials from the larger chamber and resetting the time cycle of the timer.

The present invention relates generally to apparatus for use in the rendering of fats and oils from slaughter house waste products and the like. More specifically, the present invention relates to a new and useful steam and/or compressed air operated pump for moving and preheating row untreated waste products from a feed hopper to the first stages of the rendering process.

Inedible slaughter house wastes such as fats, fieshings stripped from hides, offal, hide trimmings and the like can be treated and refined into clear fats and oils and protein solids having a low fat content. The wastes are first collected in a hopper, coarsely ground or prebroken and then pumped and preheated by direct steam injection to the first stage of the rendering process. Large solid waste such as bone pieces, heads, and long stringy fibrous wastes such as fieshings or hide trimmings can easily entangle, foul and damage any rotating pump part. Therefore, prior art pumps of the rotary or centrifugal type are practical only when such waste materials have been fully ground. Pumps employing a reciprocating piston are more suitable for pumping unground wastes but such pumps are also subject to excessive wear due to the nature of the unground waste materials. Accordingly, it is an object of my invention to provide a new and useful steam and/ or compressed air operated pump which has no moving parts and which is able to handle coarse ground slaughter house waste materials with a minimum of wear.

Other devices such as blow tanks, which discharge by compressed air or steam have also been used to pump slaughter house wastes from a collector or hopper to the first stage of the rendering process. While blow tanks have no moving parts and are able to handle unground wastes, they have certain other drawbacks. For example, blow tanks are relatively large and discharge their entire contents wtih each blow. Furthermore, a relatively large force must be applied to slaughter house waste to start the material moving. Once the material has started to move, however, only a relatively small force is required to keep the material moving. In blow tanks, pressurization does not stop until after discharge starts. The result is that once discharge starts, a blow tank will forcibly expel the entire contents of the tank in an uncontrolled explosion-like reaction. Therefore, it is another object of my Patented Nov. 12, 1968 ice invention to provide a steam and/ or compressed air operated pump which expels a small amount of unground waste in a controlled flow.

Another disadvantage of other pumps which use a blast of compressed air or steam to discharge is that such pumps must be gravity filled. These pumps waste space as they either must be located on a level below the feed hopper or must use a conveyor system for loading. Therefore, it is a further object of my invention to provide a pump which is vacuum filled thereby eliminating wasted space or the need for conveyor loading apparatus.

Reciprocating piston type pumps load under a vacuum formed on the intake stroke of the piston; but over a period of use, piston rings and gaskets wear, destroying the effectiveness of the pump. Therefore, it is yet another object of my invention to provide a steam and/or air operated pump which fills under a vacuum and which has a minimum of moving parts subject to wear.

These and other objects, advantages, and the characterizing features of my invention will become more apparent upon consideration of the following description thereof in conjunction with the accompanying drawing depicting the same, in which the sole figure is a schematic representation of the pump and associated apparatus of my invention. While it should be understood that the pump of my invention can be operated with either a com pressed gas or steam or with a mixture of both, for purposes of describing my invention and for illustration only, I shall describe the pump as being steam operated.

Referring now in detail to the drawing, the figure shows the pump of my invention generally designated at 10. Pump 10 is generally L-shaped having a base leg 12 and an upright leg generally designated at 14. Base leg 12 has its end 16 open for discharge into a conduit 18. Discharge from open end 16 is controlled by a knife valve 20. Base leg 12 is provided with an inlet 22 for charging the pump with coarse ground slaughter house waste material from a hopper 24. Inlet 22 is opened and closed by a knife valve 26. Knife valves are preferred in open end 16 and inlet 22 because this type of valve is not easily fouled by solids. Base leg 12 can be of any suitable length but preferably it should be kept as short as possible to save space by permitting upright leg 14 to be positioned adjacent the hopper 24.

As shown in the figure, upright leg 14 has an upper portion or steam chamber 28 and a lower portion or pump chamber 39. Steam chamber 28 is smaller in diameter than pump chamber 30 and has a smaller volume than pump chamber 30 for purposes set forth hereinbelow. Steam chamber 28 communicates through a steam line 29 with a source of high pressure steam (not shown). Flow of steam from the high pressure source through pipe 29 and into steam chamber 28 is controlled by a steam valve 32 located in steam line 29. Also communicating with steam chamber 28 is a steam vent pipe 34 which extends into hopper 24 and terminates in a plurality of downward opening sparger vents 36. Venting of steam from chamber 28 is controlled by a steam vent valve 38.

Connected with steam line 29 at a point intermediate steam chamber 28 and valve 32 is a vacuum line 40. Line is in turn connected to a vacuum chamber 50. A vacuum pump 44 runs constantly to evacuate vacuum chamber for purposes set out hereinbelow. Flow through line 40 is controlled by a valve 46.

Opening and closing of knife valve 26, steam vent valve 38 and valve 46 is controlled by a timer 42 which operates any suitable valve opening and closing mechanisms 25, 37 and 35 respectively. Opening and closing of knife valve 20 is controlled by a pressure switch 48 which acts responsive to pressure in steam chamber 28 to activate any suitable valve opening and closing mechanism 19. Timer 42 further controls the opening and pressure 3 switch 48 controls the closing of steam valve 32 by activating any suitable valve opening and closing mechanism 31.

To describe the method of operation of my apparatus and by way of illustration only I shall describe the pump cycle as beginning with all valves, except steam vent valve 38, closed. With vent valve 38 open, any steam remaining in steam chamber 28 from the previous pump cycle can vent through vent pipe 34 and sparger vents 36 and into hopper 24. Low pressure steam venting downward from sparger vents 36 preheats and loosens the slaughter house waste material contained in hopper 24 adjacent knife valve 26 to facilitate movement of the waste material into base leg 12 when knife valve 26 is opened. After a very short interval, timer 42 causes vent valve 38 to close and knife valve 26 to open, allowing the waste material to fall by gravity into base leg 12. Valve 46 is now opened by timer 42 to connect steam chamber 28 to the partial vacuum of vacuum chamber 50. This reduces the pressure in steam chamber 28 causing atmospheric pressure in hopper 24 to force the slaughter house waste through base leg 12 and into upright leg 14. Slaughter house materials should completely fill the pump chamber 30 and overflow into steam chamber 28. After a set time interval, sufficient to permit the filling of pump chamber 30, timer 42 causes knife valve 26 and valve 46 to close. Timer 42 then opens steam valve 32 permitting high pressure steam to flow through steam line 29 and into steam chamber 28. When a predetermined pressure level has built up in steam chamber 28, pressure switch 48 causes steam valve 32 to close and causes knife valve to open. Opening valve 20 permits high pressure steam in chamber 28 to push the slaughter house wastes from pump chamber and out through the base leg open end 16 into conduit 18.

As set out hereinabove, high pressure is required to start the slaughter house wastes moving. However, once slaughter house wastes begin to move, the pressure required to maintain movement falls off rapidly. The solid steam interface, which was initially at some level in chamber 28, now falls from the smaller steam chamber 28 into the larger diameter of pump chamber 39. The relatively small volume of steam initially contained in the steam chamber expands and loses pressure rapidly. Thus, as the material begins to move, the pressure is reduced by the expansion of the relatively small volume of steam into the larger pump chamber to a value which is only sufiicient to keep the material moving.

It should be noted here that the opening of knife valve 20 by the pressure switch 48 acts to reset timer 42 which establishes the overall time cycle. Thus, after knife valve 20 is opened, a timed interval passes which is sufficient to permit the bulk of the slaughter house wastes to be pushed out of the pump under rapidly falling steam pressure without an explosive-like discharge. The timer then causes vent valve 38 to open. Steam remaining in chamber 28 now vents through vent pipes 34 and sparger vents 36 into the hopper 24. Pressure switch 48 acting responsive to low pressure in steam chamber 28 then closes knife valve 20 to complete the cycle. Timer 42 continuing to operate in timed intervals, then opens: knife valve 26 after the predetermined interval to start the next fill cycle.

For maximum efficiency, knife valve 20 should close when pump chamber 30 is just barely emptied so that the level of the steam-waste interface always falls to or just into base leg 12. If the interface falls futrher into base leg 12, steam will be able to expand along the upper portion of the base leg and escape out through open end 16 into conduit 18.

Thus, it will be appreciated that the present invention accomplishes its intended objects providing a steam operated pump which is able to move course ground slaughter house waste materials from a collection hopper to the first stage of the rendering process. Efficiency of the pump can be increased by using the steam required for preheating the waste materials to operate the pump.

Employing coacting pressure switch and timer insures the operation of the pump at maximum efiiciency by preventing the escape of steam through the base leg as described. For example, of the pressure in steam chamber 38 were to fall to the preset low level before timer 42 acts to open vent valve 38, pressure switch 48 would close knife valve 20. On the other hand, and in normal operation, the timer 42 will open vent valve 38 to intentionally reduce the pressure in steam chamber 28 to the preset low level. Employing a timer to open steam valve 32 and a pressure switch to close steam valve 32 effectively prevents slaughter house wastes from being blasted out of the pump with an explosive force by stopping the buildup of pressure before the pump is discharged. Furthermore, a relatively large diameter of pump chamber 30 with respect to steam chamber 28 allows the steam to expand and lose pressure rather rapidly during discharge which also prevents an explosive-like expulsion of waste material into conduit 18. Since the pump of the present invention employs no moving parts other than knife valves 20 and 26, which come into contact with the slaughter hose wastes, there is a minimum of moving parts to repair or replace.

It should be understood that various modifications can be made in my invention without changing the scope of the invention as claimed. For example, any residual steam remaining in steam chamber 28 after venting can be made to condense by either injecting water into the steam chamber 28 or by providing a cooling jacket about the chamber. Such condensation can be used to reduce the pressure in steam chamber 28 prior to the opening of knife valve 26 or vacuum valve 46. Thus, when knife valve 26 is opened, movement of the waste material from hopper 24 and into base leg 12 will be initiated both by gravity and by the pull of the slight vacuum created in chamber 28 by the condensing steam.

It should also be understood that upright leg 14 does not necessarily have to be vertical. For example, it can be inclined away from hopper 24 to permit a shortening of base leg 12. Such an arrangement would result in an additional saving of space.

Furthermore, it is within the skill of the art to replace timer operated knife valve 26 and pressure switch operated knife valve 20 with one way check valves. For example, a check valve used in place of knife valve 26 would be sucked open under negative pressure created by evacuating pressure chamber 28 to allow material to fall from hopper 24 and into base leg 12. Such a valve would then be forced shut under the influence of pressure produced when material is discharged. In like respect, a check valve used in place of knife valve 20 would be forced open by the pressure created in pressure chamber 28 to allow material to discharge and it would be sucked closed by the negative pressure in pressure chamber 28 when the pump is filled.

Having thus described my invention in detail, what I claim as new is:

1. A pump for fluid and semi-fluid materials comprising:

(a) a housing defining interconnecting first and second chambers, said first chamber being larger than said second chamber and having a material inlet and a material outlet;

' (b) means for filling said larger chamber with said semifluid material;

(c) pressurizing means for introducing a compressed gas into said smaller chamber; and

(d) control means for interrupting the introduction of said compressed gas into said smaller chamber and thereafter opening said material outlet to initiate discharge of the material in said larger chamber, control means including a pressure switch adapted to act responsive to pressure in said smaller chamber to interrupt the introduction of said pressurized gas into said smaller chamber and thereafter to open said material outlet and thereafter to close said material outlet.

2. A pump as set forth in claim 1, in which said pressure switch acts responsive to high pressure in said smaller chamber to interrupt the introduction of said pressurized gas into said smaller chamber and to open said material outlet.

3. A pump as set forth in claim 1, in which said pres sure switch acts responsive to low pressure in said smaller chamber to close said material outlet.

4. Apparatus for pumping slaughter house waste materials such as fat, fieshings, offal, hide trimming, and the like comprising:

(a) a feed hopper having a bottom located discharge;

(b) a pump housing defining interconnecting first and second chambers, said first chamber being larger than said second chamber and having a material inlet communicating with said discharge and a material outlet;

(c) a pressure line connecting to a source of compressed gas;

((1) a gas vent pipe extending from said housing;

(e) a timer activated filling means adapted to fill said first chamber with said waste materials;

(f) a timer actuated pressurizing means adapted to close said vent pipe and open said pressure line to pressurize said smaller second chamber; and

g) a pressure sensitive means adapted to act responsive to high pressure in said smaller second chamber to close said valved pressure line and thereafter to initiate discharge of said material from said first chamber, whereby the full pressure of fluid in said smaller second chamber is applied to said material said second chamber to initiate the discharge thereof and thereafter discharge continues under dimenished pressure as said fluid expands from said smaller second chamber intothe volume vacated by material in said first chamber. 1

5. Apparatus as set forth in claim 4 in which said vent pipe has a section extending into said hopper, said section providing with a plurality of downward opening sparger vents for sparging and preheating said waste materials with gas vented from said housing.

6. Apparatus as set forth in claim 4 in which said pressure sensitive means is adapted to recycle said first and second mentioned timer actuated means when material is discharged from said first chamber.

7. Apparatus as set forth in claim 4 in which said pump housing is generally upright, said second chamber being located above said first chamber.

References Cited UNITED STATES PATENTS 749,563 1/1904 Johnson et a1. 103-234 775,843 11/1904 Moody 103-234 1,263,287 4/1918 Ragains 1o3 234 3,106,170 10/1963 Gray "103-234 3,118,391 1/1964 Cia-battarietal. 103240 3,123,015 3/1964 Linklater 103-240 X 3,262,396 7/1966 Kingsbury 103-240 3,288,081 11/1966 McMillan 103 234 3,330,218 7/1967 Bumstead 103-234 FRED C. MATTERN, IR., Primary Examiner.

W. J. KRAUSS, Assistant Examiner. 

